Jason Allemann of JK Brickworks used LEGO to create a accurate orrery that depicts the relative rotations of the orbits of the Earth, Moon, and Sun.
Allemann has also posted building instructions for anyone looking to replicate the orrery.
A LEGO Orrery featuring the Earth, Moon and Sun. I tried to focus on making the rotation and movements as accurate as possible without making it too complex. It can be powered manually using the crank, or with a Power Functions M-Motor.
The relative sizes and distances between the objects is obviously not to scale, a concession often taken with these models. It’s also missing the tilt of the Earth and inclination of the Moon’s orbit. Perhaps some things that could be added in the future.